Treating fibrous material



Patented Aug. 28, 1928.

UNITED STATES PATENT OFFICE,

ALFRED LUTZ, OF SEEHOF, NEAR TETLOW, GERMANY, ASSIGNQR, BY IMESNE ASSIGN- MENTS, TO RONALD (3. LEE, OF BEDFORD', NEW YORK.

TREATING FIBRQUS MATERIAL.

No Drawing. Application filed March 29, 1921, Serial No. 456,759, and in Germany July 2, 1915.

Renewed May 26, 1926.

My" invention relates to improvements in the treatment 7 of fibrous material such as paper, cardboard, paper fabrics and the like with animal size, gelatins. casein, varnishes, cellulose solutions, tar asphalt and like materia s.

In the treating or impregnating of paper with a material such as animal size, gelatins and the like, it has hitherto been the practice to pass the paper. either in sheets or in webs, quickly through the impregnating medium so that the period of immersion has lasted only a few seconds. This method of treatment produces a result which is satisfactory for normal requirements, such as for writing paper, but it has the disadvantage that the impregnating material remains on the surface and is, therefore, incapable of increasing to any extent the strength of the paper. Further, if the paper is to be used for such purposes as the manufacture of articles, such as rain coats, cloaks etc., or for packing wet or greasy articles, the method hitherto employed of impregnating is unsatisfactory, notwithstanding the subsequent hardening of the impregnating medium.

It has now been found that in sizing paper new results are obtained, and that particularly, the strength of the paper when wet is increased considerably, if it is allowed to remain in the seizing bath until it has absorbed impregnating material to fill it completely.

According to the present invention, therefore, in the impregnating of paper, cardboard, paper fabrics and likematerials with animal size, gelatine, casein, varnishes and other impregnating materials, the said impregnating material is maintained at a raised temperature and the material treated is allowed to remain therein until it has absorbed as much as it can hold thereof. Preferably, the material treated is allowed to remain in the impregnating bath until it has assumed a dark shade.

In carrying the invention into effect, care must be taken to ensure that the material treated be uniformly wetted with the impregnating material and in treating the material in webs the webs are reeled up in the impregnating bath. I have found that the stren th of the material treated when wet, whet er operated on in sheets or in webs, is sufficient to enable it to stand the subsequent treatment, even if it has remained for some hours in the impregnating bath.

In carrying my invention into efii'ect, I pre-' fer maintaining the impregnating bath at a temperature of about 40 C., so as to obtain the desired penetration, and the material treated is reeled in the size together with supporting felt, parchment paper, wax cloth, or the like, to'protect it from strains.

I prefer employing a sizing and impregnating solution to which has been added sodium hydroxide or lactic acid. For I have ascertained that by employing sodium hydroxide or lactic acid the sizing or impregnating solution will penetrate deeper into the material treated than is possible with-the sizing and impregnating solutions at present in use.-

The action of these chemicals cuts the viscous colloidal sizing solution and allows it to penetrate into the fibrous material much more readily, so that the impregnation is not only accomplished more quickly but a more thorough degree of impregnation is attained than can possibly be secured with a plain sizing solution such as has been commonly used heretofore. For the purpose of the present application, I prefer to use the term .accelerator to refer to the chemicals such as sodium hydroxide and lactic acid which areadded to the sizing solutions. The presence of the accelerator not only produces the results above .mentioned, but also permits a more equal and complete difiiusion of the sizing composition through the fibrous material. I have found that the best results are obtained by allowingthe material to stand for a considerable time after being impregnated to allow the sizing to become thoroughly diffused.

Sodium hydroxide lye is added in quantities up to about 2 percent calculated on the weight of the liquid, and with such an addition it is possible .to employ a 30 per cent to 40 per cent animal size solution, and cause it to penetrate the material treated, such. as paper or cardboard, whereas, with such a' thick solution alone the sizing and impregnating solution would merely remain on the surface.

When employing lactic acid this may he I added in quantities up to '30per cent calculated on the quantity of dry size.

The temperature of the sizing and impregnating solution should not be allowed to rise above 45 C. for any length of time, as otherwise a decomposition of the size is likely to occur. 4

' According to the present invention also,-

the' material treated may be hardened after the impregnating operation by introducing it directly into the ,hardening bath, after removing the surplus impregnating material orthe hardening medium may be applied by painting, spraying,-brushing, blowing or the like and subsequently stacking, piling or reeling the material treated so as to allow the hardening medium time to take effect. In

this operation, supporting felt or the like may be employed to protect the material treated from strains. B painting, spraying, brushing, blowing or ikewise applying the hardemng medium, the quantity thereof applied can be carefully proportioned so that the drying is cheapened and the hardening medium, such as formalin, is completely absorbed,

whereby obnoxious odours during the opera- 1 tion are eliminated.

If the hardening operation be allowed to continue as long as possible, the resulting product is particularly resistant to water and it is possible by the present process to produce(paper or cardboard which, with a cone spon ing percentage of moisture, is similar in its mechanical properties to leather or' gutta percha. The product obtained by the process according to the present invention is impervious to grease.

Hardening may preferably be carried out with Inethylolformamide, a com ound having the formula HCONHC ,.OH. The

A methylolformaniide may be added to the size,

large quantities, for example 20 per cent, calculated on the weight of the paper or other material treated, a very flexible leather-like product is obtained the to the hygroscopic.

properties of the methylolformamide.

My im roved method is not only applicable to fibrous material in general but is also particularly adapted for the treatment of completely finished and sized papers which can e treated by my method without changing the appearance of the paper in any particular but imparting to it at the same time veryunusual and unexpected properties and attributes in the following respects 1st. The dry strength of the paper is increased from 20% to 100% and the web 6th. Makes the oilproof glassine paper water resistant.

I claim: r 1. The process of treating fibrous material which consists in immersing said material in web form in a-bath of-a gelatinous impregnating material, applying to said impregnated web a hardening agent consisting of methylolf ormamide, and then allowing the web to stand to get progressive hardening of the impregnating material by the hardening agent. A

-2. An improved method of sizing fibrous material which consists in treating the material with a gelatinous sizing. composition to impregnate it, keeping the composition and material in contact until complete saturation of the material is reached, maintaining the composition and material at a temperature above normal during the impregnating, then applying a quantity of hardening medium to said material proportioned to'the quantity of sizing material soaked u and supporting the material during the har ening step.

3. An improved method of sizing fibrous material which consistsin treating the material with a gelatinous sizing composition to impregnate it, keeping the composition and material in contact until complete saturation of the material is reached andmaintaining the composition and material at a temperature, above normal during the impregnating then treating the material with methylolformamide.

4. An improvedmethod of sizingfibrous material which consists intreating the material with a' gelatinous sizing com-position, to which an accelerator hasbeen added, to impregnate-it, keeping the composition and materialin contact until complete saturation of the material is reached and maintaining the composition and material at a temperature above normal during the impregnating th'en treating the materlal with methylolformamide substantially as described.

5. An improved method of sizing fibrous material which. consists in treating the material with a gelatinous-sizing composition to which sodium hydroxide has been added to impregnate it, keepin the composition and material in contact until complete saturation of the material is reached and maintaining the composition and material at a temperature above normal during the impregnating then- "l proportioned to the uantitg' of e treating the material with methylolformamide. l

- 6. An improved method of sizing fibrous material which consists in treating the materi- 5 a1 with a latinous sizing composition to impregnate 1t, maintaining the composition and material at atemperature above normal during the impregnating, then applying a quantity of hardening medium to said material material soaked up, ,win in t materi thehardenin medium and owing it to standin roll orm while the hardening me dium acts on the sizing composition.

7. An improved method oi sizing fibrous material which consists in treating the material' with a gelatinous sizing composition to impregnate it, maintaining the composition and material at a temperature above normal during the im regnatinz. then appl g a-quantity of bar 'ening'mediunidirect y to into roll "form immediately a er afiplication of saidmaterial proportioned to the quantity of sizing material soaked up,. and superpo'sing 25,

adjacent layers-of the material immediately after application of the hardeniii medium to" confine the hardening mediu m I superposed layers whereby the hardening! mfifat 0 tween the dium acts on the sizing composition whi material is. in the for moi su erp'osed layers.

treating fil roua 8. An-im r'oved methodo material V0011 ists essentially of i i 4 the fibrous material ith a gehtinous Sim-n g com 'tion then a plying to the fibrous materia while in web em a quantity of hardening medium proportional to'the quantity of sizing material soaked u of the hardening medium and allowi ng it to stand in roll form while the hardemng medium acts on the sizing com 'tion.

the web into roll form immediate y after application In-testimony whereof I my signature. 1 

